1. Field of the Invention
The present invention pertains to systems for effecting relative movement of a flowable substance, more specifically to marine vessels, and even more particularly to hulls and propulsion means for such vessels.
2. Description of the Background
Prior U.S. Pat. No. 4,505,684 discloses a vessel the hull of which has longitudinally extending, open-ended tubes along its full length. The tubes housed propellers which could propel the vessel by moving water through the tubes. The tubes were configured to effect velocity and pressure changes in the relatively moving water in a manner generally opposite that of a conventional venturi.
This prior art vessel incorporated several features reminiscent of aircraft technology. For example, the aforementioned reverse venturi operation was enhanced by a ramlike effect if the vessel moved through the water at a sufficient speed. Also, the propellers within the longitudinal tubes were further enclosed within shorter rings, reminiscent of shrouds used in ducted fan type thrust systems for jet aircraft.
Another feature of this prior art vessel which differed from conventional marine vessel design was the formation of convergent bow and stern configurations by a series of intersecting flat segments, rather than by smooth curves.
The present invention represents further development of an improvement over the vessel disclosed in prior U.S. Pat. No. 4,505,684. As will be explained more fully below, the present invention increases the potential speed per unit horsepower by several different expedients. The present invention also provides easier access for repair purposes, and even facilitates the potential beaching of certain embodiments for such repairs at low tide.
A particular problem with the prior art vessel was that each tube had to be divided into two laterally spaced apart branches in order to accommodate an engine and shaft to drive the respective propeller. The present invention provides an improved way of interconnecting the engine and rotor, and which also serves several other useful functions, such as enhancement of structural strength.
These and other improvements and developments will be made apparent by the description of the present invention itself.